The field of finite element exterior calculus (see [1]}) explains how some finite elements can be related to others through the action of the exterior derivative.
Such spaces can be part of a de Rham complex, which is the chain of spaces obtained by application of the exterior derivative.
For instance, taking the divergence of a field in the \(\mathrm {RTc}^f_k\)  space yields a field in the discontinuous Galerkin space \(\mathrm {DG}_{k-1}\) .
The main families of finite elements that form de Rham complexes are captured in the periodic table of finite elements [2]}.
